<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">

    </div>
    <div class="one">one1</div>
    <div class="one">one2</div>
    <div class="one">one3</div>
    <script>
        var app = document.getElementById("app")
        // console.log(app);

        //nodelist 
        var all = document.querySelectorAll(".one")
        console.log(all);
    </script>
</body>
</html>